Heat exchanger with internal slotted manifold

ABSTRACT

A heat exchanger that includes a manifold tube having a plurality of spaced apart openings formed through its wall in flow communication with a flow passageway, and a plurality of stacked flat tube elements each including a first plate and a second plate defining a flow channel therebetween, the plates each being provided with an aperture therethrough, the apertures in the first and second plates being substantially in alignment with each other. The manifold tube is received through the apertures in the first and second plates of each of the flat tube elements with each of the spaced apart openings in flow communication with the flow channel of a respective one of the flat tube elements. During assembly, the wall of the manifold tube is radially enlarged so that an outer surface of the manifold tube engages an inner surface surrounding the aperture in each of the first and second plates to secure the flat tube elements to the manifold tube. Also provided is a stacked plate heat exchanger having a manifold tube with an error proofing hole for ensuring a baffle cup is in place in the manifold tube, and a stacked plate heat exchanger having a manifold tube and a port fixture having an annular flow way in communication with a flow passage in the manifold tube through a plurality of radially spaced openings through the manifold tube.

BACKGROUND OF THE INVENTION

[0001] This invention relates to heat exchangers, and in particular tostacked plate heat exchangers using slotted manifold tubes.

[0002] Current heat exchangers for use in automobiles are well known andare generally of the flat plate type constructed with alternating andadjacent laterally extending fluid flow and air flow passages. Flatplate heat exchangers that use slotted manifold tubes are known,including for example the heat exchangers illustrated in U.S. Pat. No.5,908,070 (Kato et al.) and U.S. Pat. No. 6,073,686 (Park et al.) inwhich the opposite ends of flat fluid flow tubes are inserted into slotsprovided in manifold tubes. Inserted plate type heat exchangers can becumbersome to assemble, and be prone to leak or otherwise fail at higherfluid pressures.

[0003] Other types of slotted manifold heat exchangers, for example asshown in U.S. Pat. No. 5,560,425 (Sugawara et al.), have been proposedthat use flat fluid flow tubes that have flanges for abutting against aportion of the manifold adjacent a corresponding slot in the manifold.Abutting plate type heat exchangers can also be cumbersome to assembledue to difficulties in maintaining manifold and plate alignment prior tobrazing, and also may have failure concerns at higher fluid pressures.

[0004] Still a further type of slotted manifold heat exchange isillustrated in U.S. Pat. No. 3,605,882 (P. R. Smith et al.) in which themanifold is inserted through holes provided in the flat fluid flowtubes, with tube spacers being positioned on the manifold betweenadjacent flat tubes in order to secure the flat tubes in place. Such aconfiguration can be complex to assemble. Another slotted manifold heatexchanger can be seen in U.S. Pat. No. 2,511,084 (J. C. Shaw), in whichthe manifolds are also inserted through holes provided through coreelements. In such a configuration, the core elements are securedtogether by bolts, independently of the manifolds.

[0005] Thus, there is a need for a slotted manifold heat exchanger thatis easy to assemble and that is high pressure resistant. A heatexchanger and corresponding assembly method that require relativelylittle manufacturing adjustments or retooling to produce heat exchangersof varying length, width or height are also desirable.

SUMMARY OF THE INVENTION

[0006] According to one aspect of the invention, there is provided aheat exchanger that includes a manifold tube having a wall defining aflow passage therethrough and having a plurality of spaced apartopenings formed through the wall in flow communication with the flowpassageway, and a plurality of stacked flat tube elements each includinga first plate and a second plate defining a flow channel therebetween,the plates each being provided with an aperture therethrough, theapertures in the first and second plates of each of the tube elementsbeing substantially in alignment with each other. The manifold tube isreceived through the apertures in the first and second plates of each ofthe flat tube elements with each of the spaced apart openings in flowcommunication with the flow channel of a respective one of the flat tubeelements. The wall of the manifold tube and the apertures arerespectively sized that an outer surface of the manifold tube engages aninner surface surrounding the aperture in each of the first and secondplates to secure the flat tube elements to the manifold tube, the flattube elements being supported by the manifold tube. The openings formedthrough the manifold tube wall may vary in size along a length of themanifold tube.

[0007] According to another aspect of the invention, there is provided amethod of assembling a stacked plate heat exchanger, including steps of(a) providing a manifold tube having a wall defining a flow passagetherethrough and having a plurality of spaced apart openings formedthrough the wall in flow communication with the flow passageway; (b)providing a plurality of flat tube elements each including a first plateand a second plate defining a flow channel therebetween, the plates eachbeing provided with an aperture therethrough, the apertures in the firstand second plates of each of the flat tube elements being substantiallyin alignment with each other; (c) positioning the manifold tube throughthe apertures in the first and second plates of each of the flat tubeelements with each of the spaced apart openings in flow communicationwith the flow channel of a respective one of the flat tube elements; and(d) radially expanding at least portions of the manifold tube such thatmanifold tube engages each of the first and second plates about theapertures thereof to secure the flat tube elements to the manifold tube.The heat exchanger may be brazed after expansion of the manifold tube.

[0008] According to another aspect of the invention there is provided isa heat exchanger comprising a manifold tube having a wall defining afluid flow passage therethrough and a stack of flat tube elementsconnected to the manifold tube and each having a flow channeltherethrough in fluid communication with the fluid flow passage. Abaffle cup having a wall engages an inner surface of the manifold tubewall, the manifold tube wall having an error proofing hole formedtherethrough at a location where the baffle cup wall is positioned, thehole being sized such that a visual check can be performed to ensurethat the baffle cup is in place. The error proofing hole is sealablycovered by the wall of the baffle cup.

[0009] According to still another aspect of the invention, there isprovided a heat exchanger comprising a manifold tube having a walldefining a fluid flow passage therethrough, a stack of flat tubeelements connected to the manifold tube and each having a flow channeltherethrough in flow communication with the fluid flow passage, and aport fixture having a collar providing an annular flow way surroundingan annular area of the manifold tube wall having a plurality of radiallyspaced openings formed therethrough. The annular flow way is in flowcommunication with the fluid flow passage through the radially spacedopenings, the port fixture having a connecting member extending from thecollar and defining a fluid passageway in flow communication with theannular flow way.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Preferred embodiments of the invention will now be described, byway of example, with reference to the accompanying drawings, in which:

[0011]FIG. 1 is an elevational view of a preferred embodiment of a flatplate heat exchanger according to the present invention;

[0012]FIG. 2 is a perspective view of the heat exchanger of FIG. 1;

[0013]FIG. 3 is a partial sectional perspective view of the heatexchanger of FIG. 1;

[0014]FIG. 3A is a partial sectional elevational view showing an inletport mounted to a manifold tube of the heat exchanger;

[0015]FIG. 4 is a plan view of a plate pair tube element of the heatexchanger of FIG. 1;

[0016]FIG. 5 is an exploded elevational view of a plate pair tubeelement;

[0017]FIG. 6 is a perspective view of a turbulizer of the plate pairtube element;

[0018]FIG. 7 is an elevational view of a manifold tube of the heatexchanger;

[0019]FIG. 8 is a plan view of the manifold tube;

[0020]FIG. 9 is a perspective view of a bracket for the heat exchangeraccording to one embodiment of the invention;

[0021]FIG. 10 is a schematic illustration of an assembly process for theheat exchanger;

[0022]FIG. 11 is a partial sectional perspective view of the heatexchanger of FIG. 1, showing a hydraulic bladder being used to expand amanifold tube;

[0023]FIGS. 12A and 12B illustrate, in elevational view, the use of atapered pin mandrel to expand a manifold tube;

[0024]FIG. 13 is a partial elevational view showing a manifold tubehaving slot openings in accordance with a further embodiment of theinvention;

[0025]FIG. 14 is a partial elevational view showing a manifold tubehaving slot openings in accordance with still a further embodiment ofthe invention;

[0026]FIG. 15 is a partial elevational view showing a flat tube elementmounted on a manifold tube in accordance with a further embodiment ofthe invention;

[0027]FIG. 16 is a partial elevational view showing a manifold tubehaving slot openings in accordance with a further embodiment of theinvention;

[0028]FIG. 17 is a simplified elevational view showing a furtherembodiment of a heat exchanger in which a baffle cup is used to separatethe manifold tubes;

[0029]FIG. 18 is a sectional perspective view of a baffle cup;

[0030]FIG. 19 is a partial elevational view showing an error proofinghole for the baffle cup;

[0031]FIG. 20 is a simplified elevational view of yet a furtherembodiment of a heat exchanger according to the present invention;

[0032]FIG. 21 is a plan view of the heat exchanger of FIG. 20;

[0033]FIG. 22 is a partial sectional perspective view of a heatexchanger according to another embodiment of the invention;

[0034]FIG. 23 is a plan view of a bracket of the heat exchanger of FIG.22;

[0035]FIG. 24 is a plan view of a further bracket configuration;

[0036]FIG. 25 is a plan view of yet a further bracket configuration;

[0037]FIG. 26 is a sectional plan view of a further port fitting mountedon a tube manifold;

[0038]FIG. 27 is an elevational view of the further port fitting;

[0039]FIG. 28 is an elevational view of yet another port fitting;

[0040]FIGS. 29 and 30 are partial sectional perspective views of furtherflat tube element embodiments; and

[0041]FIG. 31 is a elevational view of still a further embodiment of aheat exchanger according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0042] The structure, operation, and method of assembly of the heatexchanger of the subject invention will now be described, with likereference numerals used throughout to refer to similar parts ofdifferent embodiments of the heat exchanger.

[0043] Referring to FIGS. 1, 2 and 3, a flat plate heat exchangeraccording to one preferred embodiment of the present is shown generallyby reference numeral 10. The heat exchanger 10 is a single pass heatexchanger which may be used in an automotive application such as atransmission oil cooler or power steering fluid cooler, however thefeatures of the present invention can be applied to a wide range of heatexchangers for different applications and the heat exchanger 10 of FIG.1 is provided as just one example of a heat exchanger according to thepresent invention. The heat exchanger 10 includes a first manifold tube12 and second manifold tube 14, which in the single pass configurationillustrated function as an intake manifold tube and an out take manifoldtube respectively. A plurality of elongate flat tube elements 16 arearranged in parallel fashion on the manifold tubes 12,14. The flat tubeelements 16 each include a first plate 18 and a second plate 20 sealedtogether to form a flow passage way 21 there between. Air passages 22are located between adjacent flat tube elements 16, and corrugated fins24 are located in air passages 22, fins 24 being in thermal contact withadjacent flat tube elements 16 for providing a high surface area forheat exchange between the fins 24 and air flowing through the airpassages 22.

[0044] As best seen in FIG. 3, the manifold tube 12 includes a series ofslots 42 that are longitudinally spaced along and extend through thecylindrical wall of the manifold tube 12. The slots 42 are arranged sothat their length runs transverse to the longitudinal axis of themanifold tube 12. The flat tube elements 16 are each arranged along themanifold 12 so that each of the tube elements 16 is aligned with arespective one of the tube slots 42, and more particularly, so that thefluid passage 21 provided through each of the tube elements 16 is inflow communication with the passage 30 provided through the manifoldtube 12 through the respective openings provided by manifold tube slots42.

[0045] Similar slots are provided along the cylindrical wall of the outtake manifold tube 14, and the out take ends of the flat tube elements16 are arranged on the out take manifold 14 such that an out take end ofeach of the fluid passages 21 provided through the flat plate tubeelements 16 communicates with the flow passage 34 provided through theout take manifold tube 14 by way of the slots provided along the outtake manifold tube 14.

[0046] A fluid inlet port 26 is provided on the intake manifold tube 12and a fluid outlet port 28 is provided on the out take manifold tube 14.The inlet and outlet ports 26, 28 are shown in arbitrary locations alongtheir respective manifold tubes in FIGS. 1 to 3. The inlet port 26defines a passage that is in flow communication with a fluid flowpassage 30 provided through the interior of intake manifold tube 12 suchthat a fluid can flow through the inlet port 26 into the interior of themanifold tube 12 as illustrated by arrow 32 in FIG. 3. Similarly, theoutlet port 28 defines a flow passage in communication with a flowpassage 34 defined by an interior surface of the out take manifold tube14. In the illustrated embodiment, end plates 36 and 38 without flowpassages there through are provided as the first and last plate on theheat exchanger 10.

[0047] End caps 40, which are shown in exploded view in FIGS. 1 and 2,can conveniently be used to seal the ends of the intake and out takemanifold tubes 12, 14. Brackets 43 may be positioned along the manifoldtubes 12, 14 to permit the heat exchanger 10 to be secured in position.

[0048] Thus, during operation of the heat exchanger 10, the fluid to becooled enters the heat exchanger 10 through the inlet port 26 and flowsinto the passage 30 in the intake manifold tube 12. From the intakemanifold tube 12, the fluid is dispersed through slots 42 into theplurality of fluid passages 21 that are provided through the flat tubeelements 16. The fluid exits the fluid passages 21 through correspondingslots provided on the out take manifold tube 14 to enter the fluidpassage 34 provided by the out take manifold tube 14. As the fluidtravels across the heat exchanger 10 through the fluid passages 21, itsheat energy is drawn off by corrugated fins 24, which in turn are cooledby air flowing through the air passages 22. The cooled fluid leaves theout take manifold tube 14 through the outlet port 28.

[0049] An overview of the heat exchanger 10 having been provided, thedetails of the structure and fabrication of the elements of the heatexchanger 10 will now be discussed in greater detail with reference tothe Figures.

[0050] As can be seen in FIGS. 1-3, the flat tube elements 16 eachinclude openings at their opposite ends through which the manifold tubes12 and 14 are internally received. With reference to FIGS. 4 and 5,which show a top plan view and an exploded elevational view,respectively, of a preferred embodiment of one of the flat tube elements16, each of the first and second plates 18,20 includes a elongatesubstantially planar central portion 56. Inwardly offset flanges 58 arelocated along the longitudinal edges of the plates 18 and 20, forminglongitudinal peripheral edges. End flanges 60 extend between the ends oflongitudinal flanges 58, thus forming end edges on the plates 18, 20.Thus, flanges 58 and 60 collectively form a continuous inwardly offsetedge portion that surrounds the planar central portion 56. When theplate pairs 18 and 20 are joined together, the offset longitudinalflanges 56 of one plate abut against the longitudinal flanges of theother plate, and similarly the end flanges 60 of plate abut against theend flanges 60 of the other plate. As will be explained in greaterdetail below, in one preferred embodiment the first and second plates18, 20 are sealably connected along the longitudinal edges and end edgesthereof through a brazing process. In some embodiments, soldering oradhesive bonding could be used.

[0051] The longitudinal flow passage 21 is defined between the centralplanar portions 58 of the first and second plates 18, 20. A turbulizeror turbulator 62 is, in a preferred embodiment, located within the fluidchannel 21 that is formed between the planar portions 56. Greater detailof one possible turbulizer 62 configuration is shown in FIG. 6. Theturbulizer 62 includes a series of undulations or convolutions formedtherein to create turbulence in the fluid flow and in this way increaseheat transfer in the heat exchanger. In some embodiments, turbulizersmay not be used, or could be replaced by dimples, ribs or ripples formedon the plates 18,20.

[0052] With reference to FIG. 4, an opening 44 is provided through oneend of the flat tube element 16 for receiving the intake manifold tube12, and a second spaced-apart opening 46 is located at the other end ofthe flat tube element 16 for receiving the out take manifold tube 14.With reference to FIG. 5, the opening 44 is provided by alignedapertures 48 that are pierced through the first and second plates 18,20, and similarly, opening 46 is provided by aligned apertures 50 thatare pierced through opposite ends of the plates 18, 20. The apertures 48and 50 are pierced through end portions of the outwardly offset planarportions 56 such that when the flat tube elements are assembled, theopenings 44 and 46 are both in flow communication with the fluid passage21 that is defined between the plates 18, 20. As best seen in FIG. 3Aand 4, the apertures 44,46 are, in a preferred embodiment, arranged suchthat an annular portion 23 of the flow channel 21 extends around thecircumferences of the manifold tubes.

[0053] A peripheral flange 64 defines an inner circumference of each ofthe apertures 48. The flange 64 extends outward (i.e. away from the flowchannel) from the outer surface of the central planer portion 56. Theperipheral flanges 64 are integrally formed on their respective plates,and provide an overlap joint between the flat tube elements 16 and therespective manifold tubes 12,14, as can best be seen in FIG. 3A.

[0054] In a preferred embodiment, the plates 18, 20, are roll formed toform the central planar portion 56 and longitudinal flanges 58, afterwhich the roll formed raw plate is lanced at a desired length andperipheral end flanges 60 are end formed. The apertures 48 and 50 areformed by piercing and subsequently extruding the peripheral flange 64.As shown in FIG. 4, the longitudinal flanges 58 can extend further intothe centre of the plates 18, 20 near the apertures 48, 50 to formshoulders 59 to abut against each other to support the plates 18,20 nearthe openings 44,46, but still provide the annular flow path 23 aroundthe outer facing portions of the manifold tubes. Shoulders 59 provideincreased strength around the apertures 48,50.

[0055] The use of roll formed plates conveniently allows plates ofvarying lengths to be made with minimal assembly line changes required.Plates 18,20 could also be formed using other techniques, including forexample, stamping, however such alternatives may not be as flexible asroll forming for permitting changes in plate length.

[0056]FIG. 7 shows an elevational view of a preferred embodiment of theintake manifold tube 12, which is basically a cylindrical wall havingmanifold tube slots 42 spaced along a length thereof. In one preferredembodiment, an inlet opening 68 is provided for the inlet port 26. Anoutwardly extending flange 70, which in the illustrated embodiment isannular, is optionally provided at one end of the manifold tube 12 inorder to provide a stop for the end plate 36 or 38 during assembly ofthe heat exchanger. The slots 42 are preferably formed by using a diepunch with internal die support, or a saw, however it would beappreciated that other slot forming methods could be used, for example,saw cutting, milling, piercing, laser cutting, or lancing.

[0057] With reference to FIG. 8, an outer diameter of the manifold tube12 is illustrated as having a dimension D1. Prior to assembly of theheat exchanger 10, the outer diameter D1 is less than an inner diameterD2 (see FIG. 4) of the opening 44 through the plate pair 16, in order toallow the plate pair 16 to be slidably mounted on the manifold 12. Theout take manifold tube 14 is basically identical to the intake manifoldtube 12, and has an outer diameter D1 that, prior to assembly, is lessthan an inner diameter D2 of the opening 46 through each of the flattube element 16 so that the plate pair elements can be mounted thereon.

[0058] With reference to FIG. 3A, in a preferred embodiment, the inletport 26 includes a cylindrical collar 98 through which the intakemanifold tube 12 can pass. A cylindrical connecting wall 100 defining aninlet passage extends transversely from the collar 98. Conveniently, thecollar 98 can be supported by the peripheral flanges 64 of opposing flattube elements as illustrated in FIG. 3A in such a manner that it can bepivoted to a desired position during heat exchanger assembly prior tomanifold tube expansion. In the illustrated embodiment of FIGS. 1 to 3,the outlet port 28 is identical to and mounted in the same manner as theinlet port 26.

[0059]FIG. 9 shows in greater detail a mounting bracket 43 according toone embodiment of the invention for use on the intake or out takemanifold tube 12,14 side of the heat exchanger 10. Each mounting bracket43 has first clip part 146 including spaced-apart C-shaped clips 148,149, each of which defines respective contacting surfaces 150, and acentral portion or spacer member 152 extends between and connects theclips 148,149. A second clip part 154, has spaced apart C-shaped clips156,157. Each clip 156,157 defines a respective contacting surface 158.A central portion or spacer member 160 extends between and connects theclips 156,157. The C-shaped clips 148, 149 are dimensioned to receiveone flat tube element 16, and the C-shaped clips 156, 157 a second flattube element 16. Preferably, the C-shaped clips are dimensioned tofrictionally engage their respective flat tube element with sufficientforce to hold the bracket in place until brazing occurs.

[0060] The inlet and outlet ports 26, 28 and brackets 43 as describedabove are only one example of several different inlet and outlet portand bracket configurations that can be used with the present invention,and examples of further alternatives will be provided further below.Alternative manifold tube and flat tube element configurations to thosedescribed above can be used as well, and examples of furtheralternatives will also be provided below. But first, a description ofthe elements of a preferred embodiment of the heat exchanger 10 havingbeen provided, assembly of the elements to form the heat exchanger 10will now be described.

[0061] With reference to the schematic flowchart of FIG. 10, asindicated by brace 92, in one preferred assembly method a core heatexchanger stack (indicated by reference numeral 108 in FIG. 11) isassembled from end plates 36,38, first and second plates 16, 18,turbulizers 62 and fins 24. In particular, the end plate 38 ispositioned (step 90-1) and a fin 24 placed along it (step 90-2), afterwhich a first plate 16 is added (step 90-3), followed by a turbulizer 62(step 90-4), followed by a second plate 18 (step 90-5) such that thefirst and second plates 16,18 define fluid flow channel 21 therebetweenin which the turbulizer 62 is positioned. As indicated in FIG. 10 byline 94, building up the core stack through the method sequence ofadding a fin 24, a first plate 16, a turbulizer, and a second plate 18continues until the core stack reaches a predetermined height (which, inthe example shown in FIGS. 1-3, includes five plate pairs), after whicha final fin 24 is added and the core stack topped off with end plate 36(step 90-6). As the core stack 108 is being assembled, all the corestack components are aligned as illustrated in FIGS. 1 to 3, with plateapertures 48 substantially aligned and plate apertures 50 substantiallyaligned. End plates 38 and 36 also have corresponding apertures providedthere through.

[0062] Preferably, fittings, namely the inlet and outlet ports 26,28 andbrackets 43 are then positioned on the core stack 108 as required (step90-7). Once the fittings and brackets are added to the core stack, themanifold tubes 12 and 14 are slidably inserted through the correspondingaligned apertures in the assembled core stack (step 90-8). The annularflanges 70 on the ends of the manifold tubes 12 and 14 act as stopmembers to assist in positioning the manifold tubes. Preferably, thecore stack 108 is then compressed (step 90-9) until the slots 42 in themanifold tubes 12 and 14 are each aligned with a respective flow channel21 through a corresponding flat tube element 16.

[0063] The manifold tubes 12 and 14 are each then internally expanded toincrease their respective outer circumferences so that they eachsecurely engage an inner circumference of the apertures 48 and 50,respectively, of each of the plates 18 and 20 thereby effectivelylocking the plate pairs 16 in place (step 90-10). As mentioned above,prior to expansion, the manifold tubes 12 and 14 each have a respectiveouter diameter D1 (FIG. 8) that is less that an inner diameter D2 (FIG.4) of the corresponding plate apertures 48 and 50, in order tofacilitate assembly of the heat exchanger. During expansion, at leastthe portions of the manifold tube walls adjacent the plate apertures 48and 50 are enlarged such that the enlarged diameter exceeds the innerdiameter D2 of the apertures. Thus after expansion, the enlargedmanifold tubes 12 and 14 each engage substantially the entirecircumference of the plate apertures 48 and 50, respectively (in thepreferred embodiment that is shown in the drawings, an overlap joint isformed between each of annular flange 64 and the manifold tubes that itsurrounds), preventing any further movement of the plates 16,18 relativeto the enlarged manifold tubes 12 and 14.

[0064] With reference to FIG. 11, in one preferred embodiment ahydraulic bladder 102 is placed inside each of the manifold tubes 12 and14, and expanded by pumping hydraulic fluid through an inlet 106 toradially enlarge the manifold tubes in a substantially uniform manneralong their entire lengths through radial pressure applied uniformlythroughout the manifold tubes in the direction indicated by arrows 104.The use of a uniform radial pressure along the length of the manifoldtubes decreases any axial loading during the expansion process. Axialloading is generally not desired, especially in longer manifold tubes,as it can result in deformation that is exacerbated by the slottednature of the manifold tubes.

[0065] It will be appreciated that alternative expansion methods canalso be used. For example, in shorter manifold tubes where axial loadingis not as great a concern, a tapered pin mandrel can be used to expandthe manifold tubes. FIGS. 12A and 12B show pre-expansion andpost-expansion, respectively, views illustrating the use of a steppedtapered pin mandrel 106 to radially expand the manifold tube 14 in thevicinity of each of the slots 42 to achieve locally pronounced expansionat the points along the manifold tube 14 where the flat tube elements(not shown in FIGS. 12A and 12B) are engaged by the manifold tube. Ifdesired, in embodiments in which a hydraulic bladder is used to effectexpansion, bands could be provided around the bladder to localizeexpansion at the points along the manifold tubes in the manner shown inFIG. 12B.

[0066] With reference again to FIG. 10, subsequent to manifold tubeexpansion, end caps 40 are placed on the manifold tubes 12 and 14, forexample by a swage or press-fit operation (step 90-11), after which theentire heat exchanger 10 assembly is sent to a brazing oven (step90-12). At least the first and second plates 18, 20 of the heatexchanger are preferably braze clad such that in the brazing oven, theflat tube elements are sealaby brazed along their respective edges, theperipheral flanges 64 about the plate apertures 48, 50 are sealablybrazed about their entire circumferences to the manifold tubes 12,14,respectively, the end caps 40 are sealably brazed in place, and the fins24 and end plates 36,38 are all secured by brazing.

[0067] Compression of the core stack 108 (step 90-9) prior to radialexpansion of the manifold tubes is performed in the preferred assemblymethod to compensate for shrinkage of the core stack that occurs duringbrazing. In some heat exchanger configurations, if the flat tubeelements are locked in place by expansion of the manifold tubes withoutpre-compression of the core stack, then the centre area of the corestack may bow inwards due to shrinkage in the brazing oven. Preferably,compression of the core stack is applied preferentially to the coreplate stack 108 in the areas closer to the manifold tubes 12,14, wherethe greatest resistance to compression will generally be experienced.

[0068] The core plate stack 108 could be assembled using methodsdiffering from that shown in FIG. 10. For example, in an alternativepreferred embodiment, the manifold tubes 12,14 are loaded into afixture, and the core plate stack 108 built up by sliding the platesonto the manifold tubes one at a time, or in groups, along withalternating fins and turbulizers, rather than assembling the entire coreplate stack 108 and then inserting the manifold tubes as described abovein respect of FIG. 10.

[0069] The configuration of the present invention provides a heatexchanger with a relatively high burst strength as the slotted manifoldtubes 12,14 are supported internally within the apertures of each of theplates 18,20. Such configuration also provides a relatively strong jointbetween each of the flat tube elements and each of the manifold tubes.Assembly is uncomplicated as the use of expanded manifold tubes tosecure the plates 18,20 in place prior to brazing reduces the need forany additional spacers or collars to be mounted on the manifold tubes tohold the plates in position.

[0070] With relatively few assembly line changes, the heat exchangerconfiguration and assembly method of the present invention can be usedto produce a number of variations of the heat exchanger. For example,heat exchangers of different heights can be produced by using longer orshorter manifold tubes (for taller and shorter heat exchangers,respectively) and a corresponding increased or decreased number of flattube elements and fins. Heat exchangers of different lengths (asmeasured from manifold tube to manifold tube in the illustratedembodiment) can be produced by roll forming longer or shorter first andsecond plates 18, 20, and longer or shorter end plates 36,38, and usinglonger or length-wise shorter fins 24. Heat exchangers of differentwidths can be produced by roll forming wider or narrower first andsecond plates 18, 20, and wider and narrower end plates 36,38, and usingwider or narrower fins. If desired, larger or smaller diameter tubemanifolds can be used with corresponding changes being made to theapertures pierced through the plates 18,20. The spacing between flattube elements 16 can be changed by changing the spacing of the manifoldslots 42 along the tube manifolds 12,14, and using higher or lower fins24. It will thus be appreciated that features of the present inventioncan be used in the production of heat exchangers having varied length,width and height, without significant assembly line tooling changes.

[0071] The present invention also provides flexibility in fitting andbracket placement. The location of inlet and outlet ports 26, 28, can bevaried relatively easily by using manifold tubes with inlet and outletopenings 68 in a different location, and then adding the inlet and/oroutlet ports 26, 28 to the core stack 108 at a location corresponding tothe different inlet and/or outlet openings. In practice the positions ofthe fittings in this invention can easily be adjusted to suit heatexchanger flow distribution constraints or to correspond to preferredfluid supply connector locations. One or both of the manifold tubes12,14 could also be configured without side inlets or outlets, andinstead have an inlet or outlet, respectively, at a manifold tube endrather than an end cap 40.

[0072] Some examples of alternative preferred embodiments of the presentinvention will now be described.

[0073] It will be appreciated that in some embodiments, the slots 42 maybe replaced by openings of a different configuration, for examplecircular or oval, or each individual slot 42 could be replaced with aplurality of openings. By way of example, FIG. 13 shows a manifold tube14 having radial rows of circular openings 172 and radial rows of squareopenings 174 in place of slots 42. Such openings may be radially locatedabout part of or the entire circumference of the manifold tube.

[0074] In a further preferred embodiment of the invention, the sizes ofthe slots 42 along one or both of the manifold tubes 12, 14 are variedalong the length thereof. For example, with reference to FIG. 14, insuch further preferred embodiment, the opening defined by the slot 42designated by S2 is larger than the opening defined by the slot 42designated by S1. The larger size of slot 42-S2 may be the result ofslot 42-S2 having a greater height than slot 42-S1 (slot height beingparallel to the longitudinal axis of the manifold tube 14), or may bethe result of slot 42-S2 having a greater length than slot 42-S1 (slotlength being transverse to the longitudinal axis of the manifold tube),or may be a result of both of these factors. In embodiments where aplurality of openings are used in the place of a single slot, the sameeffect can be achieved by using more openings to communicate with theflow channels of flat tube elements where a larger opening area isdesired. Varying the size of the slot openings along the manifold tubesmay be used to improve flow distribution through the heat exchanger 10.In the embodiment of FIG. 14, the slot openings become progressivelylarger from the bottom to the top of the manifold tube 14. In someembodiments, the slots may be grouped with slot size increasingprogressively for groups of slots, with for example a group of threelongitudinally adjacent slots having the same size, and then the nextthree slots having a different size and so on. The size of therespective slot openings through the intake and out take manifold tubes12, 14 in flow communication with the inside channel through a givenflat tube element 16 need not be identical in all applications, howeverslot to slot centre spacing on the two manifold tubes should besubstantially identical to maintain proper plate pair spacing throughoutthe core stack 108.

[0075] The height of slots 42 is limited to less that the distancebetween the plates 18 and 20. Larger slot heights can be used if thespacing between the plates 18 and 20 is increased in the area around themanifold tubes. By way of example, FIG. 15 shows an embodiment of theinvention in which the spacing between first and second plates 18 and 20of tube element 16 is increased in an annular area 110 surrounding themanifold tube 14 to accommodate a slot 42 having a height greater thanthe flow channel defined by planar portions 56.

[0076] The slots 42 along the manifold tubes 12,14 may, in someembodiments of the present invention, be directed in some other mannerthan inward towards the centre of the heat exchanger. For example, FIG.16 shows an out take tube manifold 14 in which the slots 42 face theends 60 of the plates making up flat tube elements 16, rather thanfacing towards the centre of the heat exchanger. Such a configurationforces the fluid flowing through the flat tube elements 16 into the endsof such elements.

[0077] In some embodiments of the invention, spacing of the slots 42,and the corresponding spacing of the flat tube elements 16 may be variedalong the length of the manifold. For example, with reference to FIG. 7,spacing H1 could be different than spacing H2.

[0078] Another embodiment of a heat exchanger according to the presentinvention is shown in a simplified view indicated by reference number111 in FIG. 17. The heat exchanger 111 is similar in construction andoperation to the heat exchanger 10 as described above except for thedifferences noted below. As with heat exchanger 10, the heat exchanger111 includes a stack of alternating fins 24 and flat tube elements 16that extend between a first manifold tube 12′ and a second manifold tube14′. The manifold tubes 12′ and 14′ each have spaced apart slots alongtheir respective lengths that connect flow passages inside the manifoldtubes 12′ and 14′ with flow channels in the flat tube elements 16.However, cup baffles 112 are sealably secured inside each of themanifold tubes 12′ and 14′, effectively turning the heat exchanger intotwo separate heat exchangers, as identified by reference numbers 114 and116, for two different fluids. In the illustrated embodiment of the heatexchanger 111, as indicated by arrow 118, a first fluid flows into theportion of the manifold tube 12′ above the cup baffle 112. The firstfluid then flows through slots in the upper portion of manifold tube12′, through corresponding plate pair flow tubes 16, and subsequentlyinto the out take manifold tube 14′, and then out of the manifold tube14′ as indicated by arrow 120. As indicated by arrow 122, a second fluidflows into the portion of the manifold tube 12′ below the cup baffle112. The second fluid then flows through slots in the lower portion ofmanifold tube 12′, through corresponding plate pair flow tubes 16, andsubsequently into the out take manifold tube 14′, and then out of themanifold tube 14′ as indicated by arrow 124. In such embodiment, thefirst and second fluids are kept separated in the heat exchanger 111.Various features could be varied between the two sub-heat exchangers114, 116 depending on the desired treatment for the first and secondfluids. For example, higher flat tube element 16 spacing could be usedfor one sub-heat exchanger than the other and/or larger manifold slotscould be used in one sub-heat exchanger than in the other.

[0079] In some configurations a baffle cup 112 having a calibratedopening therethrough may be located in either one or both of the intakeor out take manifold tubes 12′ and 14′ to control fluid flow therein. Insome embodiments, baffle cups may divide only one of the manifold tubes12′, 14′, and only a single fluid be used in the heart exchanger, whichthen assumes a double pass configuration. For example, a baffle cup 112could be used only in the first manifold tube 12′ to divide it in twochambers as indicated in FIG. 17, the baffle cup 112 in second manifoldtube 14′ omitted, and the second manifold tube 14′ capped with no outletor inlet ports provided therein. In such configuration, fluid would flowinto the portion of first manifold tube 12′ above the baffle cup 112 asindicated by arrow 118, through the upper three flat tube elements 16shown in FIG. 17 and into the second manifold tube 14′, then into thethree lower flat tube elements 16, and back into the first manifold tube12′ below the baffle cup 112, and out of the manifold tube 12′ in theopposite direction of arrow 122. From this example, it will beappreciated that further baffle cups could be used to configure the heatexchanger as a multi-pass exchanger.

[0080] The baffle cups 112 can each be stamped from a brazing sheet, andwill typically be installed after manifold tube expansion has beencarried out. An example of one possible configuration of a baffle cup112 is shown in greater detail in FIG. 18, in which the baffle cup 112includes a circular disc like member 113 having an cylindrical wall 115formed about its outer peripheral edge. Wall 115 provides an overlapjoint with the wall of the manifold tube 12′ or 14′ in which the bafflecup 112 is inserted. Preferably the baffle cup is sized so that thecircumference of the outer surface of wall 115 is small enough toslidably fit into the expanded manifold tube 12′ or 14′, but largeenough to frictionally engage the inner surface of the wall of themanifold tube 12′ or 14′ so that the baffle cup 112 does not moveunintentionally prior to brazing once positioned in place. In oneembodiment, the baffle cup 113 is inserted into its respective manifoldtube using a rod fixture of calibrated length to correctly position thebaffle cup. In a preferred embodiment of the invention, an errorproofing hole 117 is provided through the wall of the manifold tubes12′, 14′ in alignment with the location where the baffle cup 12 shouldbe positioned once installed. As seen in FIG. 19, the error proofinghole 117 is positioned to align with and be covered by the baffle cupwall 115 when the baffle cup is mounted in the manifold tube 12′, 14′.The error proofing hole 117 provides for a visual check to ensure thebaffle cup is in place as an operator can look into the hole to ensurethat it is blocked by wall 115. The error proofing hole 117 alsoprovides a functional check as a test fluid fed into the manifold tubewill leak out of the hole if the baffle cup 112 is not sealably inplace. It will be appreciated that the baffle 112 and error proofinghole 117 combination could be used for flat plate tube heat exchangerconfigurations other than the expanded manifold tube configuration ofthe present invention.

[0081] The heat exchanger of the present invention could be divided intoseparate sub-heat exchangers using configurations other than the bafflecup divided configuration shown in FIG. 17. In this regard, FIGS. 20 and21 illustrate yet another embodiment of a heat exchanger 126 of thepresent invention. The heat exchanger 126 is similar to the heatexchanger 10 described above, except for the differences noted below.Like the heat exchanger 10, the heat exchanger 126 includes a stack ofalternating flat tube elements 16(1)-16(4) and fins 24. However, theheat exchanger includes a pair of intake manifold tubes 12A and 12B, anda pair of out take manifold tubes 14A and 14B. As illustrated in FIG.21, the manifold tubes 12A, 12B, 14A and 14B are each internallyreceived through openings provided through each of the flat tubeelements 16(1)-16(4). The intake manifold tubes 12A and 12B are slottedso that neither intake manifold tube is in flow communication with thesame flow channel 21 through the same flat tube element, and similarlythe out take manifold tubes 14A and 14B are slotted so that neither outtake manifold tube is in flow communication with the same flow channel21 through the same flat tube element. For example, in the illustratedembodiment, the first intake manifold 12A receives a first fluid throughan inlet port as indicated by arrow 128. The first intake manifold 12Ahas slots in communication with the flow channels through flat tubeelements 16(1) and 16(3), but does not include slots along the portionsof its length that pass through flat tube elements 16(2) or 16(4).Similarly the first out take manifold tube 14A has slots incommunication with the flow channels through flat tube elements 16(1)and 16(3), but does not include slots along the portions of its lengththat pass through flat tube elements 16(2) or 16(4), such that the firstfluid passes from the first intake tube manifold 12A through flat tubeelements 16(1) and 16(3) to the first out take manifold 14A, and out ofthe heat exchanger through an outlet port as indicated by arrow 134.

[0082] Each of the second intake manifold tube 12B and the second outtake manifold tube 14B have manifold slots 42 in communication with theflow channels through flat tube elements 16(2) and 16(4), but not withalternating flat tube elements 16(1) and 16(3). Thus, a second fluid canflow into the second intake manifold tube 12B as indicated by arrow 130,through the flat tube elements 16(2) and 16(4) into second out take tubemanifold 14B, and then out of the heat exchanger as indicated by arrow132. As best seen in FIG. 21, the inner manifold tubes 12B and 14Bpreferably have smaller diameters than the outer manifold tubes 12A and14A in order to facilitate flow of the first fluid by the innermanifolds as indicated by arrows 136 and 138. Conveniently, the manifoldslots 42 on the inner manifold tubes 12B and 14B can be outwardlydirected (i.e. towards the outer manifold tubes 12A and 14A) in order toforce the second fluid to travel closer to the outer ends of the heatexchanger.

[0083] As noted above, the heat exchanger configuration of the presentinvention permits different fittings and brackets to be used. In thisregard, FIG. 22 illustrates yet another embodiment of a heat exchanger178 of the present invention. The heat exchanger 178 is similar to theheat exchanger 10 described above, except that inlet and outlet ports 26and 28 are replaced by differently configured inlet and outlet ports 182(inlet port not shown in FIG. 22), and brackets 43 have been replaced bydifferently configured mounting brackets 180.

[0084] The bracket 180 includes an L-shaped mounting plate 184 that isconnected to a cylindrical wall forming a closed collar 186 that issized to receive wall of a manifold tube 12 or 14 therein. FIG. 23 showsa plan view of the bracket 180 having closed collar 186. Other bracketconfigurations can be used in which an open snap-on style collar isused. For example FIG. 24 shows a further bracket 188 having a hookshaped open collar 190 for engaging the manifold tube between two flattube elements, and FIG. 25 shows a bracket 192 having a Y-shaped opencollar having opposed semi-circular portions 194 for engaging themanifold tube. The hook shaped collar 190 and collar portions 194 arepreferably braze clad and appropriately dimensioned and sufficientlyresilient so that the brackets 188, 192 can be snapped on the manifoldtube at a desired location and will stay in place until brazing.Alternatively, the collar 190 and collar portions 194 could be crimpedto secure them in place.

[0085] Turning again to FIG. 22, as indicated above, an alternative portfitting 182 is shown mounted to the manifold tube 14. The port fitting182, which can function as either an inlet or outlet port, is shown insectional plan view and elevational view, respectively, in FIGS. 26 and27. Fitting 182 includes an annular collar 200 for receiving themanifold tube 12 or 14. The collar 200 includes a cylindrical wall 202that is capped on opposite ends thereof by disk-like end plates 204 and206, each of which has a circular opening 208 therethrough for receivingthe manifold tube 12 or 14. The inner surfaces of the cylindrical wall202 and end plates 204,206 collectively define an internal cavity 210through which the manifold 12 or 14 passes. The internal cavity 210 hasdiameter, transverse to the longitudinal axis of tube manifold 12,14,that, is greater than the diameter of the tube manifold 12, 14 such thatan annular flow passage 212 is defined between the tube manifold 12,14and the inner surface of wall 202. A cylindrical connecting member 214extends radially from the outer surface of the collar wall 202, and theconnecting member 214 defines an fluid flow passage 216 that is in flowcommunication, through an opening 218 provided in the wall 202, with theannular flow passage 212. A frustal-conical flange is provided at anextending end of the connecting member 216 for internally engaging aconnector hose or like flow passage connected to the connecting member216.

[0086] The port fitting 182 is intended to be used in conjunction with amanifold tube 12,14 having a plurality of radially spaced flow openings222 provided therethrough which are each in flow communication with theannular passage 212. The port fitting and manifold tube combination ofFIGS. 22, 26 and 27 permits fluid to be forced into or drawn frommultiple locations about the radius of the manifold tube, providingimproved flow management in some heat exchanger applications. Theannular collar 200 preferably has a height that corresponds to thespacing between two flat tube elements 16 so that it can fit betweenadjacent tube elements as shown in FIG. 22.

[0087]FIG. 28 shows a further embodiment of a port fitting, indicatedgenerally by reference 224, that is similar to port fitting 182 exceptthat it is a banjo-type fitting adapted for use at the end of a manifoldtube 12,14. In such configuration, an opening 208 for receiving the tubemanifold 12 or 14 is only provided at an one end plate (plate 204 in theFIG. 28), and the other end plate (end plate 206 in FIG. 28) is sealedand acts as a stop for engaging an end of the manifold tube 12,14. Inbanjo-type fitting, openings 22 could be spaced apart from the end ofthe manifold tube as shown in FIG. 28, or could be notches formed aboutthe radius of the bottom of the tube.

[0088] In some embodiments where the fitting 182 is to be used betweentwo adjacent flat tube elements 16 that each encircle the manifoldtubes, integral top plates 204 and 206 may be omitted from the collar200, and functionally replaced by the facing surfaces of the twoadjacent flat tube elements 16.

[0089] In some embodiments, the collar 200 and passage 212 may extendonly partially around the manifold tube. In some embodiments, the collar200 could be secured in place prior to brazing by radial expansion ofthe manifold tube. In some embodiments, the collar could be formed froma non-metal such as a polymer material and secured by epoxy or otheradhesive. It will be appreciated that the collar fitting and manifoldtube combination of FIGS. 26 and 27 could be used in heat exchangershaving a variety of different configurations, including for exampleconventional stacked plate exchangers in which the plate ends arereceived within the manifold tubes.

[0090] The flat tube elements 16 have been described as comprising twoseparate opposing plates 18, 20 that are joined together by brazingalong their respective edges. It will be appreciated that flat tubeelements in which the opposing plates are formed in another manner canbe used in the present invention. By way of example, FIGS. 29 and 30illustrate partial sectional perspective views of two further flat tubeelements 16A and 16B, respectively, each of which defines a flow channel21. The first and second plates 18 and 20 of flat tube element 16A arepreferably roll formed longitudinally together as a single sheet withlongitudinal flanges 252 and 254 provided along opposite side edgesthereof. Apertures 48, 50 for the manifold tubes (not shown in FIG. 21)are then pierced through each of the plates 18, 20, and the flange aboutthe apertures extruded, after which the plates 18, 20 are foldedtogether about a common longitudinal edge 250 until the flanges 252 and254 contact each other. With respect to the flat tube element 16B, insuch configuration the edges 256, 258 joining the first and secondplates 18, 20 are seamless.

[0091] Although the heat exchanger 10 has been shown in its preferredembodiment as including a flange 64 about the apertures 48, 50 in firstand second plates 18, 20, in some applications a flangeless aperture maysuffice, in which case a somewhat weaker butt joint rather than anoverlap joint would be formed between the plates 18, 20 and each of themanifold tubes 12, 14. Furthermore, in some embodiments, the annularflow path 23 may not be present about the entire circumference of themanifold tubes.

[0092] The heat exchangers of the present invention as described abovehave each included corrugated fins 24 located between adjacent flat tubeelements 16. In some embodiments, such fins may be omitted, or replacedwith ribs or other protrusions formed on the flat tube elements 16. Inembodiments where the fins are omitted, spacing between the adjacentflat tube elements 16 may be provided by enlarged bosses around theapertures, such as the enlarged annular area 110 as shown in FIG. 15. Insome fin-less embodiments, removable spacers may be positioned betweenadjacent tube elements 16 to support them during assembly.

[0093] Another embodiment of a heat exchanger according to the presentinvention is shown in a simplified view indicated by reference number270 in FIG. 31. The heat exchanger 270 is similar in construction andoperation to the heat exchanger 10 as described above except for thedifferences noted below. In heat exchanger 10, the manifold tubes 21 and14 are connected by a bypass tube 272 through which fluid can flowdirectly from one manifold tube to the other, bypassing the core stack108. A calibrated baffle 274 or other flow control means such as athermostatically actuated valve can be located in the bypass tube 272 tocontrol flow therethrough. The tubes 12, 14, and 272 may be integrallyformed as a single U-shaped unit.

[0094] In some embodiments, only a single expanded manifold tube may beused, with the second manifold having a different configuration, suchas, for example, the cup configuration shown in U.S. Pat. No. 5,634,518issued Jun. 3, 1997.

[0095] The above description has anticipated that the heat exchangercomponents are made out of metal. However, other materials such asplastics or other polymers could be used in some applications for all orsome of the heat exchanger components. In a polymer embodiment, manifoldtubes may be thermally expanded rather than or in addition to beingpressure expanded. Alternatively, the manifold tube may not be expanded,but a friction fit between the flat plate tube element and the manifoldtubes used in combination with bonding effected, for example, thermally,ultrasonically, or through the use a bonding agent or adhesive.

[0096] The heat exchanger of the present invention can be adapted for anumber of different applications for use, among other things, inautomobiles, recreational vehicles, and fuel cell thermal managementsystems. In addition to the transmission oil and power steering fluidcooling applications mentioned above in respect of heat exchanger 10,the present invention can be adapted for use in, among other things,engine oil cooling, hydraulic fluid cooling (which requires highpressure strength) and air conditioning applications (for bothevaporator and condenser applications). Selective variable manifold tubeslot size and positioning can be particularly helpful in evaporatorapplications where flow distribution sensitivity is high.

[0097] It will also be apparent to those skilled in the art that inlight of the foregoing disclosure, many other alterations andmodifications are possible in the practice of this invention withoutdeparting from the spirit or scope thereof. Accordingly, the scope ofthe invention is to be construed in accordance with the substancedefined in the following claims.

What is claimed is:
 1. A heat exchanger comprising: a manifold tubehaving a wall defining a flow passage therethrough and having aplurality of longitudinally spaced apart openings formed through thewall in flow communication with the flow passageway; and a plurality offlat tube elements located along a longitudinal axis of the manifoldtube, each including a first plate and a second plate defining a flowchannel therebetween, the plates each being provided with an aperturetherethrough, the apertures in the first and second plates of each ofthe tube elements being substantially in alignment with each other, themanifold tube being received through the apertures in the first andsecond plates of each of the flat tube elements with each of the spacedapart openings in flow communication with the flow channel of arespective one of the flat tube elements; the wall of the manifold tubeand the apertures being respectively sized that an outer surface of themanifold tube engages an inner surface surrounding the aperture in eachof the first and second plates to secure the flat tube elements to themanifold tube, the flat tube elements being supported by the manifoldtube.
 2. The heat exchanger of claim 1 wherein the manifold tube isradially expanded at least along portions thereof where the outersurface engages the first and second plates of the flat tube elements.3. The heat exchanger according to claim 1 wherein the inner surface ofthe aperture in the first and second plates that is engaged by the wallof the manifold tube is defined by an integral peripheral flangeextending outward from the plate such that an overlap joint is formedbetween the wall and the peripheral flange, and the wall is brazed tothe peripheral flange of each of the plates to seal a juncturetherebetween.
 4. The heat exchanger according to claim 1 wherein thefirst and second plates each have a substantially planar elongatecentral portion surrounded by a planar edge portion inwardly offset fromand parallel to the planar central portion, the first and second platesof each flat tube element being joined together with the planar centralportions spaced apart from each other to define the flow channel and theoffset edge portion of the first plate abutting against the offset edgeportion of the second plate.
 5. The heat exchanger or claim 1 wherein,in at least some of the flat tube elements, the first plates and secondplates are identical to each other.
 6. The heat exchanger according toclaim 1 wherein the flat tube elements are spaced apart from each otherdefining lateral passageways therebetween, and including fins located inthe lateral passageways and in thermal contact with the flat tubeelements.
 7. The heat exchanger of claim 1 wherein the spaced apartopenings include openings of more than one size.
 8. The heat exchangerof claim 1 wherein the spaced apart openings are progressively largeralong a length of the manifold tube.
 9. The heat exchanger of claim 1including at least one flat tube element having a flow channel that isin flow communication with the flow passage of the manifold tube througha plurality of radially spaced openings formed through the manifold tubewall.
 10. The heat exchanger of claim 1 wherein the flat tube elementsare spaced apart from each other and the spacing distance between theflat tube elements varies along the manifold tube.
 11. The heatexchanger of claim 1 wherein the flow passage through the manifold tubeis divided into first and second flow chambers with some of the flattube elements being in flow communication with the first chamber andothers of the flat tube elements being in flow communication with thesecond flow chamber.
 12. The heat exchanger of claim 11 wherein a bafflecup located within the manifold tube divides the manifold tube into thefirst and second flow chambers, the baffle cup having a cylindrical wallhaving an outer surface in engagement with an inner surface of themanifold tube wall.
 13. The heat exchanger of claim 12 wherein an errorproofing opening is provided through the manifold tube wall at alocation where the wall of the baffle cup overlaps the manifold tubewall, the error proofing opening being sized to permit visualconfirmation of the presence of the wall of the baffle cup.
 14. The heatexchanger of claim 1 including a mounting bracket having a collarengaging the manifold tube between two adjacent flat tube elements. 15.The heat exchanger of claim 1 wherein at least some of the flat tubeelements include first and second plates having portions that are spacedfurther apart from each other closer to the manifold tube than furtherfrom the manifold tube to define a higher flow channel, relative to thelongitudinal axis of the manifold tube, nearer the manifold tube thanfurther from the manifold tube.
 16. The heat exchanger of claim 1including a port fixture mounted to the manifold tube, the port fixturedefining a flow passageway that is in flow communication, through a portopening in the manifold, with the flow passage through the manifoldtube, the port fixture including a collar surrounding an annular area ofthe manifold tube.
 17. The heat exchanger of claim 16 wherein the collarof the port fixture defines an annular fluid flow way about the annulararea of the manifold tube, the annular area having a plurality ofradially spaced openings through which the annular fluid flow way is inflow communication with the flow passage through the manifold tube. 18.The heat exchanger of claim 17 wherein the collar is located between twoadjacent flat tube elements.
 19. The heat exchanger of claim 17 whereinthe port fixture is a banjo-type fitting and the collar engages an endof the manifold tube.
 20. The heat exchanger of claim 1 wherein theouter surface of the manifold tube engages substantially an entirecircumference of the inner surface of the aperture in each of the platesin a butt-joint fashion.
 21. The heat exchanger of claim 1 including afurther manifold tube having a wall defining a flow passage therethroughand having a plurality of spaced apart openings formed through the wallin flow communication with the flow passageway, each of the plurality offirst and second plates being provided with a further aperturetherethrough, the manifold tube being received through the furtherapertures in the first and second plates of each of the flat tubeelements with each of the spaced apart openings through the furthermanifold tube in flow communication with the flow channel of arespective one of the flat tube elements, the wall of the furthermanifold tube and the further apertures being respectively sized that anouter surface of the further manifold tube engages an inner surfacesurrounding the further aperture in each of the first and second platesto secure the flat tube elements to the further manifold tube, the flattube elements being supported by the manifold tube and the furthermanifold tube; the heat exchanger further including a inlet port in flowcommunication with the flow passage through the manifold tube, and anoutlet port in flow communication with the flow passage through thefurther manifold tube.
 22. The heat exchanger of claim 21 wherein themanifold openings though the manifold tube and the further manifold tubeare inwardly oriented towards each other.
 23. The heat exchanger ofclaim 21 wherein the manifold openings through the manifold tube and thefurther manifold tube are outwardly oriented away from each other. 24.The heat exchanger of claim 21 wherein the manifold tubes are joinedtogether by a bypass manifold tube.
 25. The heat exchanger of claim 24wherein the bypass manifold tube includes fluid flow control means forcontrolling the flow of fluid therethrough.
 26. The heat exchanger ofclaim 21 further including: third and fourth elongate spaced-apartmanifold tubes each having a wall defining a flow passage therethroughand having a plurality of longitudinally spaced apart manifold openingsformed through the wall in flow communication with the flow passageway;the first and second plates of the flat tube elements each havingaligned third and fourth apertures therethrough receiving the third andfourth manifold tubes respectively, a plurality of further flat tubeelements including a first plate and a second plate defining a flowchannel therebetween, the plates of the further flat tube elements eachbeing provided with respectively aligned first, second third and fourthapertures therethrough receiving the manifold tube, the further manifoldtube and the third and fourth manifold tubes respectively, the flowchannel of each of the further flat tube elements being in communicationat a first portion thereof with the flow passage of the third manifoldtube through a respective one of the manifold openings in the thirdmanifold tube and at a second portion thereof with the flow passage ofthe fourth manifold tube through a respective one of the manifoldopenings in the fourth manifold tube; the wall of the third manifoldtube being enlarged at least along portions thereof such that an outersurface of the third manifold tube engages an inner surface surroundingthe third aperture in each of the first and second plates of the furtherflat tube element to secure the further flat tube elements to the thirdmanifold tube, the wall of the fourth manifold tube being enlarged atleast along portions thereof such that an outer surface of the fourthmanifold tube engages an inner surface surrounding the fourth aperturein each of the first and second plates of the further flat tube elementto secure the further flat tube elements to the fourth manifold tube,the flat tube elements and further flat tube elements being interspersedadjacent each other.
 27. The heat exchanger of claim 1 wherein themanifold tubes and flat tube elements are formed from polymers.
 28. Amethod of assembling a stacked plate heat exchanger, comprising: (a)providing a manifold tube having a wall defining a flow passagetherethrough and having a plurality of longitudinally spaced apartopenings formed through the wall along a length thereof in flowcommunication with the flow passageway; (b) providing a plurality offlat tube elements each including a first plate and a second platedefining a flow channel therebetween, the plates each being providedwith an aperture therethrough, the apertures in the first and secondplates of each of the flat tube elements being substantially inalignment with each other; (c) positioning the-manifold tube-through theapertures in the first and second plates of each of the flat tubeelements with each of the spaced apart openings in flow communicationwith the flow channel of a respective one of the flat tube elements; and(d) radially expanding at least portions of the manifold tube such thatmanifold tube engages each of the first and second plates about theapertures thereof to secure the flat tube elements to the manifold tube.29. The method of claim 28 wherein the flat tube elements are brazeclad, and further including, subsequent to expansion step (d), applyingheat to the manifold tube and flat tube elements to seal a joint betweeneach of the first and second plates and the manifold tube.
 30. Themethod of claim 28 wherein step (b) includes providing an integralperipheral flange around the apertures of the first and second plates,the peripheral flange of each aperture defining a circumference that isengaged by the radially expanded manifold tube.
 31. The method of claim28 wherein the manifold tube is radially expanded substantiallyuniformly along substantially an entire length thereof.
 32. The methodof claim 28 wherein the manifold tube is selectively radially expandedin a vicinity of each of the flat tube elements.
 33. The method of claim28 wherein the manifold tube is radially expanded using a hydraulicbladder.
 34. The method of claim 28 including providing fins between andin thermal contact with adjacent flat tube elements.
 35. The method ofclaim 34 including assembling a core stack by aligning stackedalternating flat tube elements and fins to a desired height with theapertures in alignment and subsequently inserting the manifold tubethrough the aligned apertures.
 36. The method of claim 34 includingassembling a core stack by building up flat tube elements on themanifold tube.
 37. The method of claim 34 including compressing a corestack comprising the flat tube elements and the fins prior to radiallyexpanding the manifold tube.
 38. The method of claim 28 wherein saidstep (b) of providing a plurality of flat tube elements includes rollforming substantially identical first and second plates each with acentral planer portion having longitudinal edge flanges provided alongboth longitudinal side edges thereof for joining the first and secondplates together; cutting the roll formed first and second plates at adesired length and forming ends thereon, and piercing the aperturesthrough the first and second plates.
 39. A heat exchanger comprising amanifold tube having a wall defining a fluid flow passage therethrough;a stack of flat tube elements connected to the manifold tube and eachhaving a flow channel therethrough in fluid communication with the fluidflow passage; and a baffle cup having a wall engaging an inner surfaceof the manifold tube wall, the manifold tube wall having an errorproofing hole formed therethrough at a location where the baffle cupwall is positioned, the hole being sized such that a visual check can beperformed to ensure that the baffle cup is in place, the error proofinghole being sealably covered by the wall of the baffle cup.
 40. A heatexchanger comprising a manifold tube having a wall defining a fluid flowpassage therethrough; a stack of flat tube elements connected to themanifold tube and each having a flow channel therethrough in flowcommunication with the fluid flow passage; and a port fixture having acollar providing a flow way surrounding at least a portion of themanifold tube wall having a plurality of spaced openings formedtherethrough, the flow way being in flow communication with the fluidflow passage through the spaced openings, the port fixture having aconnecting member extending from the collar and defining a fluidpassageway in flow communication with the flow way.
 41. The heatexchanger according to claim 40 wherein the collar includes an annularwall having a first end wall formed at one end thereof and a second endwall formed at an opposite end thereof, the first and second end wallseach having an opening therethrough through which the manifold tubepasses, the annular wall and first and second end walls defining theflow way.
 42. The heat exchanger according to claim 40 wherein the portfixture is a banjo-type fitting, and the collar includes an annular wallhaving a first end wall formed at one end thereof and a second end wallformed at an opposite end thereof, the first end wall having an openingtherethrough through which the manifold tube passes, an end of themanifold tube being positioned within the collar, the annular wall andfirst and second end walls defining the flow way.
 43. The heat exchangeraccording to claim 40 wherein the manifold tube passes internallythrough openings provided through the flat tube elements and the collarof the port fixture includes an annular wall having a first end that issealably engaged by an annular portion of one of the flat tube elementssurrounding the manifold tube, and a second end that is sealably engagedby an annular portion of a further one of the flat tube elementssurrounding the manifold tube, the annular wall and said annularportions defining the flow way.